ASTM B77-81(2001)

Standard Test Method for Thermoelectric Power of Electrical-Resistance Alloys

SCOPE
1.1 This test method covers the determination of the thermoelectric power of a metal or alloy with respect to copper when the temperatures of the junctions lie between 0 and 100oC.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.  
1.3 The values stated in inch-pound units are the preferred unit. The values in parentheses are for information only.

General Information

• Status: Historical
• Publication Date: 31-Dec-2000
• ICS: 77.120.01 - Non-ferrous metals in general
• Technical Committee: B02 - Nonferrous Metals and Alloys
• Drafting Committee: B02.10 - Thermostat Metals and Electrical Resistance Heating Materials

Relations

• Replaces: ASTM B77-81(1994)e1 - Standard Test Method for Thermoelectric Power of Electrical-Resistance Alloys
• Effective Date: 01-Jan-2001
• Replaced By: ASTM B77-07 - Standard Test Method for Thermoelectric Power of Electrical-Resistance Alloys
• Effective Date: 01-May-2007
• Referred By: ASTM B267-07(2018) - Standard Specification for Wire for Use In Wire-Wound Resistors
• Effective Date: 01-Jan-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B 77–81 (Reapproved 2001)
Standard Test Method for
Thermoelectric Power of Electrical-Resistance Alloys
ThisstandardisissuedunderthefixeddesignationB77;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope a low thermoelectric power is desired.As most electric circuits
are largely composed of copper, the thermoelectric power of a
1.1 This test method covers the determination of the ther-
resistance metal will generally be measured against copper.
moelectric power of a metal or alloy with respect to copper
when the temperatures of the junctions lie between 0 and
5. Test Specimen
100°C.
5.1 The metal or alloy to be tested shall be in the form of
1.2 This standard does not purport to address all of the
sheet, ribbon, or wire and the test specimen shall be of such
safety concerns, if any, associated with its use. It is the
length that the two ends can be readily maintained at different
responsibility of the user of this standard to establish appro-
temperatures. At each end of the specimen a copper lead of
priate safety and health practices and determine the applica-
convenient size shall be fastened. These leads shall make good
bility of regulatory limitations prior to use.
electrical contact with the specimen, such as that obtained by
1.3 The values stated in inch-pound units are the preferred
welding, brazing, or soldering. Slight impurities in the copper
unit. The values in parentheses are for information only.
have a negligible effect on the thermoelectric power.
2. Referenced Documents
NOTE 1—When necessary to specify the quality of the copper leads,
2.1 ASTM Standards:
reference should be made to Specification B 3.
B 3 Specification for Soft or Annealed Copper Wire
6. Procedure
3. Terminology
6.1 Measurement of Temperature—As a matter of precau-
3.1 thermoelectric power, Q—the electromotive force in an tion, the average temperature used in determining the thermo-
electric circuit consisting of two metals when the junctions electric power shall be approximately the same as that to which
between them have a difference in temperature of 1°C. the material will be subjected in practice, and in no case shall
3.1.1 Discussion—Experimentally, it has been found that the temperature difference between the two junctions be less
the thermoelectric power of two metals is not a constant but than 20°C. The temperature at each of two junctions shall be
depends on the mean temperature of the junctions. However, measured by a device that is sufficiently accurate to determine
over a range of temperature from 0 to 100°C it is usually the temperature difference within 5 %. A convenient method
sufficient to assume that the thermoelectric power is indepen- for determining the temperatures of the junctions is to immerse
dent of temperature so that for this range of temperature: each junction in separate oil baths maintained at the desired
temperatures. Baths that are stirred and the temperatures of
Q 5 E/~t8 2 t!
which are thermostatically controlled are to be preferred.
However, beakers of oil which are supported by blocks of
where:
metal, sand baths, or other means may be used, provided the
E = the electromotive force developed in the circuit,
thermal capacity of these assemblies is such that when the heat
t8 = the higher temperature at one junction, °C, and
is cut off their temperatures will decrease at rates less than
t = the lower temperature at the other junction, °C.
0.2°C/min. The temperature of the oil in each bath may be
determined either by a calibrated mercury thermometer or by a
4. Significance and Use
calibrated thermocouple. If the oil is not stirred, the junctions
4.1 The purpose of this method is to determine the suitabil-
shall be placed in close proximity to the temperature-
ity of different metals for use in resistance apparatus in which
measuring instrument. To ensure that the temperatures of the
junctions shall not be influenced by heat of conduction along
the specimen, the length
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